复杂查询的 CTE答案

【问题标题】：CTE For a Complex Query复杂查询的 CTE
【发布时间】：2016-11-07 18:22:00
【问题描述】：

我有这个问题：

SELECT C.[First Name],
C.[Last Name],
SUM(Salary.Emp_Salary) AS 'Current Salary'

    FROM
    (
    SELECT
        Emp_First_Name AS "First Name",
        Emp_Last_Name AS "Last Name",

        MAX(Emp_Salary_Change_Year) AS "Change Year"
        FROM Employee_Details AS e

    INNER JOIN Country AS co ON e.Emp_Country_Id = co.Country_Id
    INNER JOIN State AS s ON e.Emp_State_Id = s.State_Id
    INNER JOIN Designation AS d ON e.Desig_Id = d.Desig_Id
    INNER JOIN Salary AS sa ON e.Emp_Id = sa.Emp_Id
    WHERE Emp_Active = 1
    GROUP BY Emp_First_Name, Emp_Last_Name,
    Emp_Middle_Name, Country_Name, Desig_Name) AS C
    INNER JOIN Salary ON C.[Change Year] = Salary.Emp_Salary_Change_Year
group by C.[First Name],
C.[Last Name];

 First Name Last Name Current Salary
Chen    Chen    76000.00
Sahi    King    156000.00
Venessa Katarina    185000.00

如何使用 CTE 进行此查询？我知道使用 WITH 子句，但我无法让它工作，因为查询很复杂。我用这个作为参考：http://www.codeproject.com/Articles/265371/Common-Table-Expressions-CTE-in-SQL-SERVER 但它只包含简单的示例。

谢谢。

【问题讨论】：

您的查询是否提供了您想要的结果？
解决了。我必须在整个 cte 之后添加一个 SELECT * FROM T 子句
非常好。你能把你的结果显示为答案吗？

标签： sql sql-server tsql common-table-expression

【解决方案1】：

很简单；忽略了语法。

 WITH T([First Name], [Last Name], [Current Salary])
AS
 (

SELECT C.[First Name],
C.[Last Name],

SUM(Salary.Emp_Salary) AS 'Current Salary'

    FROM
    (
    SELECT
        Emp_First_Name AS "First Name",
        Emp_Last_Name AS "Last Name",

        MAX(Emp_Salary_Change_Year) AS "Change Year"
        FROM Employee_Details AS e

    INNER JOIN Country AS co ON e.Emp_Country_Id = co.Country_Id
    INNER JOIN State AS s ON e.Emp_State_Id = s.State_Id
    INNER JOIN Designation AS d ON e.Desig_Id = d.Desig_Id
    INNER JOIN Salary AS sa ON e.Emp_Id = sa.Emp_Id
    WHERE Emp_Active = 1
    GROUP BY Emp_First_Name, Emp_Last_Name,
    Emp_Middle_Name, Country_Name, Desig_Name) AS C
    INNER JOIN Salary ON C.[Change Year] = Salary.Emp_Salary_Change_Year
group by C.[First Name],
C.[Last Name]
)
SELECT * FROM T;

【讨论】：

【解决方案2】：

这取决于你想在哪里休息。通常可以将内联视图创建为 CTE，以使查询更易于阅读...在这种情况下，我删除了您的行视图并将其设为 CTE。

With C as (
    (
    SELECT
        Emp_First_Name AS "First Name",
        Emp_Last_Name AS "Last Name",

        MAX(Emp_Salary_Change_Year) AS "Change Year"
        FROM Employee_Details AS e

    INNER JOIN Country AS co ON e.Emp_Country_Id = co.Country_Id
    INNER JOIN State AS s ON e.Emp_State_Id = s.State_Id
    INNER JOIN Designation AS d ON e.Desig_Id = d.Desig_Id
    INNER JOIN Salary AS sa ON e.Emp_Id = sa.Emp_Id
    WHERE Emp_Active = 1
    GROUP BY Emp_First_Name, Emp_Last_Name,
    Emp_Middle_Name, Country_Name, Desig_Name)

SELECT C.[First Name]
     , C.[Last Name],
     SUM(Salary.Emp_Salary) AS 'Current Salary'
FROM C
INNER JOIN Salary 
  ON C.[Change Year] = Salary.Emp_Salary_Change_Year
GROUP BY  C.[First Name]
         ,C.[Last Name];

【讨论】：

【解决方案3】：

这取决于你想在哪里休息。通常可以将内联视图创建为 CTE，以使查询更易于阅读...在这种情况下，我删除了您的行视图并将其设为 CTE。

With C as (
    (
    SELECT
        Emp_First_Name AS "First Name",
        Emp_Last_Name AS "Last Name",

        MAX(Emp_Salary_Change_Year) AS "Change Year"
        FROM Employee_Details AS e

    INNER JOIN Country AS co ON e.Emp_Country_Id = co.Country_Id
    INNER JOIN State AS s ON e.Emp_State_Id = s.State_Id
    INNER JOIN Designation AS d ON e.Desig_Id = d.Desig_Id
    INNER JOIN Salary AS sa ON e.Emp_Id = sa.Emp_Id
    WHERE Emp_Active = 1
    GROUP BY Emp_First_Name, Emp_Last_Name,
    Emp_Middle_Name, Country_Name, Desig_Name)

SELECT C.[First Name]
     , C.[Last Name],
     SUM(Salary.Emp_Salary) AS 'Current Salary'
FROM C
INNER JOIN Salary 
  ON C.[Change Year] = Salary.Emp_Salary_Change_Year
GROUP BY  C.[First Name]
         ,C.[Last Name];

或者你可以在 ctes 上构建...

With C as (
    (
    SELECT
        Emp_First_Name AS "First Name",
        Emp_Last_Name AS "Last Name",

        MAX(Emp_Salary_Change_Year) AS "Change Year"
        FROM Employee_Details AS e

    INNER JOIN Country AS co ON e.Emp_Country_Id = co.Country_Id
    INNER JOIN State AS s ON e.Emp_State_Id = s.State_Id
    INNER JOIN Designation AS d ON e.Desig_Id = d.Desig_Id
    INNER JOIN Salary AS sa ON e.Emp_Id = sa.Emp_Id
    WHERE Emp_Active = 1
    GROUP BY Emp_First_Name, Emp_Last_Name,
    Emp_Middle_Name, Country_Name, Desig_Name),
CTE2 as (    
    SELECT C.[First Name]
         , C.[Last Name],
         SUM(Salary.Emp_Salary) AS 'Current Salary'
    FROM C
    INNER JOIN Salary 
      ON C.[Change Year] = Salary.Emp_Salary_Change_Year
    GROUP BY  C.[First Name]
             ,C.[Last Name])
SELECT * 
FROM CTE2;

【讨论】：